<!-- 相当于给模板定义一个名字, define end 必须成对出现 -->
{{ define "templates/index.html" }}
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>main page</title>
</head>
<body>
<h2>{{.title}}</h2>
</body>
</html>
{{ end }}
